This invention relates generally to ignition systems for internal combusion engines and in particular to means by which an existing internal combustion engine having a conventional ignition system may be provided with a capacitor discharge ignition system with minimal time and effort.
The capacitive discharge ignition system is generally of the type disclosed in the copending application of Thomas F. Carmichael for "Ignition System", Ser. No. 460,271, filed Apr. 12, 1974, now U.S. Pat. No. 4,056,088 and the copending application of Richard J. Maier and Thomas F. Carmichael for "Ignition System", Ser. No. 395,908, filed Sept. 10, 1973; now U.S. Pat. No. 3,941,111 both of which are assigned to the assignee of this application. Other means for converting a conventional internal combustion engine ignition system to a capacitive discharge system is disclosed in the copending application of Thomas F. Carmichael, Ser. No. 660,122, filed Feb. 23, 1976, assigned to the assignee of this application. The disclosure of each of these applications is incorporated herein by reference thereto.
Previously, the complex nature of capacitive discharge ignition systems made them prohibitively expensive for application to smaller internal combustion engines presently utilizing simple magneto ignition systems. With the development of the improved system disclosed in the first two above referenced copending applications, the number of components, package size, complexity and cost have been reduced sufficiently to allow the incorporation of such systems into these smaller sized engines such as are used in lawnmowers, chain saws, outboard motors, and the like. The ignition systems of the first two aforementioned applications are generally applicable for incorporation during original equipment manufacture of the associated engines whereas the invention of the last aforementioned application provides an inexpensive ignition replacement package whereby a wide variety of existing conventional magneto ignition systems may be easily converted to this improved capacitive discharge system by the owner of the engine subsequent to its initial purchase. However, in order to adapt certain conventional magneto ignition systems, it is necessary to provide a stator structure having provisions which allow it to be mounted on the existing mounting pads provided on the engine but yet provide a substantial shift in ignition timing so as to compensate for the differing response characteristics of a capacitive discharge system as opposed to a conventional magneto system. Also, as most small internal combustion engines have a sheet metal or plastic protective cover over the ignition system mounting area and may also have additional engine components or structure disposed nearby, severe space limitations often exist requiring specially designed stator structures in order to provide this ignition timing adjustment.
Accordingly, the present invention provides a stator structure and method of assembling a coil assembly thereto which is particularly designed to overcome these limitations as they exist in conventional Briggs and Straton five and eight horsepower engine configurations. Thus, the present invention provides means by which an owner of an implement powered by such an engine having a conventional magneto ignition system may avail himself of the advantages of a capacitive discharge ignition system at a relatively low cost, without any structural modifications to the engine itself, and without the need for any technical or specialized knowledge of ignition systems.
Additional advantages and features of the present invention will become apparent from the following detailed description taken in conjunction with the attached drawings and appended claims.